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THE BREAST / MAMMARY
GLAND:
• The breasts are specialized accessory glands of the
skin that secrete milk
• They are present in both sexes. In males and immature
females, they are similar in structure.
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THE BREAST …
• In the adult female, the base of the breast, i.e. its attached surface,
extends vertically from the second or third to the sixth rib, and in the
transverse plane from the sternal edge medially almost to the
midaxillary line laterally. However, it may extend through the deep
fascia up to the apex of the axilla (the axillary tail of Spence)
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THE BREAST …
• In young adult females, each
breast is a rounded eminence
lying within the superficial
fascia, largely anterior to the
upper thorax but spreading
laterally to a variable extent.
• The trunk superficial fascial
system splits to enclose the
breast to form the anterior and
posterior lamellae. Posterior
extensions of the superficial
fascial system connect the
breast to the pectoralis
fascia, part of the deep fascial
system.
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THE BREAST …
• Between the breast and
the deep fascia the loose
connective tissue in the
‘submammary
(Retromammary) space'
allows the breast some
degree of movement on
the deep pectoral fascia
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THE BREAST …
• The mammary gland is
firmly attached to the
dermis of the overlying
skin, by the suspensory
ligaments (of Cooper).
These condensations of
fibrous connective tissue,
particularly well developed
in the superior part of the
gland, help support the
mammary gland lobules.
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THE BREAST …
• During puberty, the breasts normally enlarge, owing in
part to glandular development but primarily from
increased fat deposition.
• Breast shape and size depend upon genetic, racial and
dietary factors, and the age, parity and menopausal
status of the individual
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NIPPLE AND AREOLA
• The nipple projects from the centre of the breast anteriorly.
The level of the nipple varies widely.
• In females, its site is dependent on the size and shape of the
breasts, but it overlies the fourth intercostal space in most
young women. In the male, the nipple is usually sited in the
fourth intercostal space in the midclavicular line.
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NIPPLE AND AREOLA
• The areola is the disc of skin that circles the base of the
nipple. It contains numerous sweat and sebaceous
glands which open directly onto the skin surface.
• The oily secretion of these specialized sebaceous
glands acts as a protective lubricant and facilitates
latching of the neonate during lactation: the glands are often
visible in parous women, arranged circumferentially as small
elevations, Montgomery's tubercles, around the areola
close to the margin
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SOFT TISSUE
• The breasts are composed
of lobes which contain a
network of glandular tissue
consisting of branching ducts
and terminal secretory lobules
in a connective tissue stroma
• Each breast consists of 15 to
20 lobes, which radiate out
from the nipple. The main
duct from each lobe opens
separately on the summit of
the nipple and possesses a
dilated ampulla just before its
termination
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SOFT TISSUE
• Each lobule is drained by a lactiferous duct, which usually
opens independently on the nipple.
• Deep to the areola, each duct has a dilated portion, the
lactiferous sinus, in which a small droplet of milk
accumulates or remains in the nursing mother. As the infant
begins to suckle, compression of the areola (and the
lactiferous sinus beneath it) expresses the accumulated
droplets and encourages the infant to continue nursing
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Vasculature of the Breast
• The breasts are supplied by
branches of the axillary artery, the
internal thoracic artery, and some
intercostal arteries.
• The axillary artery supplies blood
via the superior thoracic artery,
the pectoral branches of the
thoracoacromial
artery,
the
lateral thoracic artery and the
subscapular artery.
• The internal thoracic artery supplies
perforating
branches
to
the
anteromedial part of the breast.
• The second to fourth anterior
intercostal
arteries
supply
perforating branches more laterally
in the anterior thorax
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Venous Drainage:
Azygous vein
Internal vertebral
venous plexus
Posterior
intercostal vein
Axillary vein
Internal
thoracic vein
Intracranial saggital &
transverse sinus
CIRCULUS VENOSUS
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Clavicle and
humerus
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Lymphatic Drainage
• The lymph vessels from the medial quadrants of the breast
pierce the second, third, and fourth intercostal spaces and
enter the thorax to drain into the lymph nodes alongside
the internal thoracic artery.
• The lymph vessels from the lateral quadrants of the breast
drain into the anterior or pectoral group of axillary nodes. It
follows, therefore, that a cancer occurring in the lateral
quadrants of the breast tends to spread to the axillary
nodes. Thoracic metastases are difficult or impossible to
treat, but the lymph nodes of the axilla can be removed
surgically
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Lymphatic Drainage
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Lymphatic Drainage…
Supraclavicular
nodes
Infraclavicular
nodes
Parasternal
nodes
Axillary nodes
Sub
diaphragmatic
lymph nodes
Subperitoneal
lymph plexus
Krukenberg’s tumour
Hepatic nodes
Drainage
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Nerve Supply:
• The nerves of the breasts derive from the anterior
and lateral cutaneous branches of the 4th-6th
intercostal nerves
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Polymastia and Polythelia
• Polymastia (supernumerary breasts) or polythelia (accessory
nipples) may occur superior or inferior to the normal pair,
occasionally developing in the axillary fossa or anterior
abdominal wall. Supernumerary breasts usually consist of only a
rudimentary nipple and areola, which may be mistaken for a
mole (nevus) until they change pigmentation with the normal
nipples during pregnancy.
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Micromastia & Macromastia
• Micromastia: An excessively small breast on one side
occasionally occurs, resulting from lack of development.
• Macromastia :Diffuse hypertrophy of one or both breasts
occasionally occurs at puberty in otherwise normal girls
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Amastia
• Failure of breast development (amastia)
• Note: a nipple and/or areola may be present, but no
glandular tissue
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Gynecomastia
• Breast hypertrophy (Slight temporary enlargement of
the breasts) in males after puberty is relatively rare (<
1%) and may be age related or drug related (e.g., after
treatment with diethylstilbestrol for prostate cancer).
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witch's milk
 At birth the breasts have reached a similar developmental stage
in both sexes: the combination of fetal prolactin and maternal
oestrogen may give rise to transient hyperplasia and secretion of
‘witch's milk'.
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MUSCLES
OF PECTORAL REGION
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Muscles of Pectoral Region:
Pectoralis major & minor; Subclavius
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Pectoralis major:
Origin:
Clavicular head: anterior surface of medial half of clavicle
 Sternocostal head: anterior surface of sternum, superior six
costal cartilages, aponeurosis of external oblique muscle
Insertion:
Lateral lip of intertuberculus
sulcus of humerus
Sc
C
Actions:
♥ Adducts arm and rotates it
medially; clavicular fibers also flex
arm
Nerve supply:
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Medial and lateral pectoral
nerve
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Pectoralis minor:
Origin:
It arises from the upper margins
and outer surfaces of the
third, fourth, and fifth ribs,
near their cartilages
Insertion:
inserted into the medial border
and upper surface of the
coracoid process of the
scapula.
Actions:
drawing the scapula inferior and
medial, towards the thorax
Nerve supply: Medial
pectoral nerve
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Subclavius:
Origin:
Junction of first rib and its
costal cartilage
Insertion:
Groove on the
undersurface of the middle
third of the clavicle
Action:Stabilise the calvicle during the shoulder
movements
Nerve supply: Subclavius is supplied by the subclavian
branch of the brachial plexus, which contains fibres from
C5 and 6.
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